The computer application, developed by psychotherapist Sandra Scott in the UK, is based on an algorithm that looks for keywords and expressions of emotion to put people into different categories.

Researchers using the app found that 72 per cent of the UK's Tweeters have a dark side, with 'passionate' being the most common personality type, followed by 'materialistic', 'egoist' and 'mischievous'.

The app analyses a user's most recent 3,500 tweets before determining how much of a dark side they might have.

"Most of us have some aspect of ourselves which we are not fully aware of, a sort of 'hidden persona'," Scott said.

"It is interesting to see how we can unconsciously reveal this part of ourselves through the use of social media, which was one of the reasons I wanted to be involved in this project," Scott added.